A conventional sensor package structure includes a configuration in which a smaller chip is disposed on a substrate, and a larger chip is stacked above the smaller chip. The larger chip is electrically connected to the substrate by wire-bonding at a periphery portion thereof. However, during the wire-bonding process implemented for the conventional sensor package structure, the periphery portion of the larger chip is suspended over the substrate, and hence a force exerted on the larger chip by the wire-bonding often induces defects in the package structure. Moreover, since there is a gap easily formed between the smaller chip and the suspended periphery portion of the larger chip, it is difficult to entirely fill the gap with a packaging compound, which in turn may cause air bubbles within the gap in the conventional sensor package structure.